Supercooling is a phenomenon where even if a melt or solid is cooled below its phase transition temperature in its equilibrium state, it is not changed. Matters have their stable state according to their respective temperatures, and if the temperatures are slowly changed, the atoms of the matters can keep up with the changes of the temperature, while maintaining the stable states at their respective temperatures. However, if the temperatures are suddenly changed, the atoms of the matters cannot be changed gently to the stable states corresponding to the respective temperatures, so that the atoms of the matters are maintained still in the stable states at a starting temperature or a portion of the atoms of the matters is changed just to the state at a final temperature.
If a supercooled beverage is put in a cold cup or if impacts or vibrations are applied to the supercooled beverage, the beverage is not completely frozen or melt. That is, a slush type beverage can be provided to a consumer.
One of conventional supercooling freezers for providing supercooled beverages is disclosed in Korean Patent Registration No. 10-1205822 (issued on Nov. 22, 2012), which is illustrated in FIG. 1.
As shown in FIG. 1, the conventional supercooling freezer includes a cooling chamber 2 for accommodating liquid type beverages P therein, a heat exchanger 9 for cooling the air inside the cooling chamber 2, a cooling duct 5 for housing the heat exchanger 9 therein, an inlet 10 formed on a portion of the cooling duct 5, a cool air discharge hole 12 formed on a different position from the inlet 10 of the cooling duct 5, a cool air supply duct 6 for circulating the air inside the cooling chamber 2, an introduction hole 15 formed on one side of the cool air supply duct 6, ventilation holes 20 for blowing the air in the cool air supply duct 6 to the cooling chamber 6, and a fan 16 mounted to face the introduction hole 15 of the cool air supply duct 6. According to the conventional supercooling freezer, the cooling duct 5 absorbs the air in the cooling chamber 2 from the inlet 10 and cools the air through the heat exchanger 6. Next, the cool air is discharged through the cool air discharge hole 12. The cool air supply duct 6 is located in an up and down direction of the cooling chamber 2, and the introduction hole 15 is formed to face the cool air discharge hole 12 and at the same time to face the cooling chamber 2. Through the rotation of the fan 16, accordingly, the cool air is absorbed from the introduction hole 12 and transmitted to the cool air supply duct 6.
Under the above-mentioned configuration, the conventional supercooling freezer can supercool the beverages P accommodated in the cooling chamber 2, but the cooling duct 5 from which the cool air is supplied is located on the rear surface of the freezer. Further, the door of the freezer is frequently open and closed. Accordingly, the internal temperature of the cooling chamber 2 is not uniformly maintained. Furthermore, the beverages P located at the rear side of the cooling chamber 2 are frozen, but the beverages P located at the front side of the cooling chamber 2 are not supercooled. As the internal temperature of the cooling chamber 2 is not uniformly maintained, in addition, dew is formed on the door frequently open and closed, thus undesirably causing the loss of energy.